Caps for typewriter keys



Aug. 26, 1958 w. B. KERZNER 2,849,095

CAPS FOR TYPEWRITER KEYS Filed March 22, 1954 ggflllllllllllllllllllllg/lg Z F|G.3 FIG-4 INVENTOR ATTORNEY CAPS FOR TYPEWRITER KEYS William B. Kerzner, New York, N. Y. Application March 22, 1954, Serial No. 417,811 1 Claim. (Cl. 197-102) My invention is an improved cap, especially a cap for the end of the key of a typewriter, with atop to bear a letter or other character, the outline of which is to be reproduced on the paper in the machine.

An important object of this invention is to provide a cap which is adapted to engage the keys of a typewriter and which is so constructed that it will fit said keys securely, notwithstanding variations in the sizes of the outer ends of the key to which the cap is attached. The ends of such keys often differ in size by small amounts, but the cap of this invention is designed to have a tight frictional fit with any key to which it is attached. The nature and advantages of this invention are fully set forth in the ensuing description and the novel features are defined in the appended claim. On the drawings a preferred embodiment of my improved cap is illustrated, but I reserve the right to adopt minor alterations in structural details without omitting or materially altering any of the essential characteristics.

On said drawings:

Figure 1 is a cross section of my improved cap for the depressible end of a typewriter key;

Figure 2 shows in section my improved key affixed to a typewriter key in final position, and

Figures 3 and 4 are respectively a top and bottom plan of the cap.

The cap is preferably molded into the required form, and a suitable plastic material is employed for the purpose. The outer face of the top 1 is slightly concave, so that it can be more conveniently engaged by the operators finger when the key is struck. The cap also has a rim 2 and within the rim and concentric therewith is a low fiat bead 3 separated from the inner face of the rim by a groove 4.

This groove has inside annular surfaces 5 and 6 that converge toward the top 1. The bottom of this groove can end in a pointed angle or a flat surface 7 of slight width. The typewriter key is indicated at 8, and on its nited States Patent fifice 2,849,095 Patented Aug. 26, 1958 end is a cylindrical cup-shaped element 9 integral with the key or separate and made fast in any suitable way. The rim 10 of this element enters the groove 4 when the cap is put on the element 9.

As stated above, the inside and outside diameter of the element 7 will vary frequently by a few hundredths of an inch, and so will the thickness of the rim 10. Hence the utility of the substantially V-shaped groove 4. If this groove has a flat bottom 7, the width of this bottom must be small enough to grip the rim 10 of the element 9 snugly, when the rim 10 enters the groove 4 fully, so that the cap will be held too tight to fall off. Also if the rim 10 varies to a slight extent in diameter or thickness, it can still enter the groove 4 far enough to bind against the outer surface 5 of the groove adjacent the rim 2 or grip the inner surface 6 around the bead 3. The groove 4 has a diameter matching the diameter of the cup 9, and the cap flares away from the top slightly. It is of larger diameter around its edge than said cup. The frictional engagement of the cap with the element 9 will therefore always be suflicient to maintain the cap in position on the key and prevent displacement in the course of ordinary and regular operation of the typewriter.

The invention is thus simple in construction, easy and cheap to manufacture and quite efiicient in use and well serves all the purposes of this invention.

My improvement is quite suitable for keys on old models of typewriters of the L. C. Smith, Remington, Royal, Woodstock or Underwood make.

Having described my invention what I believe to be new is:

The combination with a typewriter key and a cylindrical cup-shaped element having a straight upstanding rim secured rigidly to the key adjacent one end thereof, of a conical cap on said element, said cap having a slightly concave top, a downwardly projecting rim flaring away from the top and being of larger diameter at its edge than said cup, and a bead inside and concentric with the rim of the cap, said bead being separated from the rim of the cap by a groove having straight sides converging towards the top, said groove having the same diameter as said cup-shaped element, said bead projecting slightly from the inner face of the top and said groove being wider between its outer edges and narrower at its inner end than the thickness of the upstanding rim of said element at the end of said key, said upstanding rim being inserted into said groove and fitting tightly therein, so that the cap is secured in place by frictional engagement with said upstanding rim.

No references cited. 

